The invention relates to lead frames for the assembly of light-emitting diodes (LED's) and more particularly to a high density lead frame that is separable into two unitary lead frames suitable for use in conventional assembly processes. Lead frames are formed into elongated strips by mechanical stamping processes.
Present practices in assembling light-emitting diodes require continuous strip lead frames that have a plurality of lead pairs held by portions of the lead frame in fixed positions relative to each other so that the light-emitting diode assemblies can be easily affixed to the sets of lead pairs in a production line. Following affixation of the assemblies, the interrelating portions of the lead frame are stamped out, leaving a plurality of separate light-emitting diode assemblies and respective lead pairs.
Prior to the assembly process, lead frames may be plated by running the strips through high speed reel to reel plating baths. Present lead frame strips are often provided in large rolls of several feet in diameter and are configured to provide a flat edge strip along which the rolls can be set and against which the strips can be run in the plating bath. One problem in handling the large rolls is a "corkscrew" effect as the strips are unwound caused by residual stress introduced in the unsymmetrical pattern of the strip during the stamping process.
Lead frames are one of the most significant cost factors in the manufacture of light-emitting diodes and the present configuration of lead frames typically uses only 20%-24% of the available blank strip, resulting in substantial waste and high material and labor costs.